Wobble butt contact switch

ABSTRACT

One of each pair of butt contact elements has a convex contact surface. In the moment after closing, or before opening of the switch, the contact elements pivot or wobble with respect to each other while in contact with each other. Arcing does not damage a second contact point at which the elements are in operating contact while the switch is at rest in the closed position, since this point is spaced apart from a first contact point at which the contact elements first abut, during closing, or separate, during opening of the switch. In a particularly useful embodiment, the switch includes fixed, spaced-apart line contacts, and a moveable conductive bridge carried on an insulated operator-controlled snap rotor element which includes means for assuring a first and second contact point by assuring pivoting or wobbling of the bridge in the moment after contact is made, or before contact is broken, with the fixed line contact elements.

United States Patent [72] Inventor Narnik O. Atakkaan Buffalo Grove, Ill.

[21] Appl. No. 865,595

[22] Filed Oct. 13, 1969 [45] Patented Nov. 2,1971

[73] Assignee Appleton Electric Company Chicago, 111.

[54] WOBBLE BUTT CONTACT SWITCH ZOO/56.2

3,472,984 10/1969 Cusick Primary Examiner David Smith, Jr. Attorney-Darbo, Robertson & Vandenburgh ABSTRACT: One of each pair of butt contact elements has a convex contact surface. In the moment after closing, or before opening of the switch, the contact elements pivot or wobble with respect to each other while in contact with each other. Arcing does not damage a second contact point at which the elements are in operating contact while the switch is at rest in the closed position, since this point is spaced apart from a first contact point at which the contact elements first abut, during closing, or separate, during opening of the switch. 1n a particularly useful embodiment, the switch includes fixed, spacedapart line contacts, and a moveable conductive bridge carried on an insulated operator-controlled snap rotor element which includes means for assuring a first and second contact point by assuring pivoting or wobbling of the bridge in the moment after contact is made, or before contact is broken, with the fixed line contact elements.

PATENTEDHUV 2 I9?! SHEET 2 BF 5 N0 PL UG- WIT HDRA WA L 2- POWER "OFF" POSITION N0 PLUG WI THDRA WAL PATENTEDHUV 2 IQYI SHEET 3 OF 5 (Zfgys min/AW PATENTEBuuv 2 mn SHEET 5 BF 5 MVW' (Z'ya WOBBLE BUTT CONTACT SWITCH BACKGROUND OF THE INVENTION The efficiency or the life of a switch can be impaired due to i the physical and chemical changes which result from the repeated opening and closing of a switch. Also, the life of a switch can be shortened when the contact surfaces are required to slide across one another, because of the wear and tear on these surfaces due to friction; Also approach of energized, opposing butt surfaces to another surface along a path which is angular with respect to the other surface increases the likelihood of arcing while the surfaces are in close proximity to each other. This invention provides for the more direct approach, i.e. along a path approximately normal to the abutting surfaces at the initial (or separating) contact points. It provides for the elimination of arc-caused damage as a factor affecting the efficiency or life of butt contacts in an electrical switch.

SUMMARY OF THE INVENTION This invention provides a wobble; butt contact switch in which at least one of the contact elements in each pair of opposing butt contact elements has a convex contact surface. The switch includes means for pivoting on one of the elements after the contact elements abut while the switch is being closed, and includes means for also pivoting the contact elements with respect to each other while the elements are still abutting prior to separation thereof when the switch is being opened. Thus, the wear and tear resulting from arcing occurs at first contact points on the contact elements, which first contact points are spaced apart from the operating or second contact positions while the switch is at rest in the closed position.

In a preferred embodiment a butt contact bridge switch has a pair of fixed, spaced-apart, open circuit contact elements and a moveable pair of electrically connected bridge contact elements adapted to form part of a conductive bridge between said open circuit contact elements. When the switch is at rest in an on" position, the bridge is pivoted to a relatively unstressed condition. When the opposing contacts are separated, i.e. in an "off" position, the bridge is forced to pivot to a relatively stressed position.

DESIGNATION OF THE FIGURES FIG. 1 is a partially cross-sectionalview sectioned approximately through the middle of a substantially circular receptacle which utilizes the butt switch of this invention. FIG. 2 is a cross-sectional view taken approximately along the line 22 of FIG. 1.

FIG. 3 is a cross-sectional view taken approximately alongthe line 3-3 of FIG. 1.

FIGS. 4 and 5 are taken along the same lines as FIGS. 2 and 3 respectively, except that the components are shown in the relative position obtained when the switch is in the power-on position. i

FIG. 6 is a perspective view of the insulating front block of the receptacle.

FIG. 7 is a bottom view of the insulating front block shown in FIG. 6.

FIG. 8 is a cross-sectional view of the insulating front block shown in FIG. 6 taken approximately along the lines 8-8 of FIG. 6.

FIG. 9 is a perspective view of the switch means rotor which resides within the lower portion of the front block shown in FIG. 6.

FIG. 10 is a cross-sectional view taken approximately along the line 10-l0 of FIG. 9.

FIG. 11 is an enlarged cross-sectional view taken approximately along the line 11-11 of FIG. 15.

FIG. 12 is an enlarged cross-sectional view taken approximately along the line 12-12 of FIG. 15.

FIGS. 13 and 14 are enlarged cross-sectional views taken as in FIG. 12, showing the relative position of the rotor, rotor contacts, and the stationary line contact as the rotor moves in the direction indicated by the arrow marked to on." FIG. 12 indicates. the position at the start of the rotor motion; FIG. 13 shows the relative position of the components at that point in the rotor motion at which initial contact between the rotor contact and line contact occurs; and FIG. 14 shows the relative position of the components when the rotor motion is completed. FIG. 15 is a partial section taken at line 15-15 of FIG. 3.

FIG. 16 is a view of a rotor contact bridge as viewed from the contact side.

FIG. 17 is a view of the rotor bridge as viewed from the rear or spring-abutting side.

DESCRIPTION OF PREFERRED EMBODIMENT Although the following disclosure offered for public dissemination, in return for the grant of a patent, is detailed to ensure adequacy and aid understanding. this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet, the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts, are found.

In the illustrated embodiment the rolling-butt switch of this invention is utilized in a receptacle, generally 40, which is shown in FIG. 1 covered by receptacle cover, generally 42. Rceptacle 40 includes as major components receptacle housing 45, mechanical programming means46, 46', automatic programmer lock means, generally 48, 48', circumferentially actuator ring 50, front insulating block, generally 51, and insulating switch-rotor. The plug used with the receptacle is not illustrated herein.

ELEMENTS FIXED TO HOUSING 45 Front insulating block 51 is fitted with circumferential shoulder 56 which seats in housing 45. Block 51 is also provided with keying notches 58 which receive detents in housing 45. Thus shoulders 56 secure block 51 against motion in the direction of the axis of housing 45, while mating of notches 58 with detents and housing 45 secure front block 51 from rotationabout the axis of housing 45. Rotatably secured in block 51 is line switch means, generally 61. The details of line switch means 61 will be discussed hereinafter. Rear block 63, having line connectors 64 secured therein abuts the rearward end 67 of front block 51 and is secured from rotation about the axis by detent 68 and front block 45 (perhaps best seen in FIG. 5 and in FIG. 7) which detent also resides in elongated indent 69 in rotor 52. Retaining ring 70 is threaded around rear block 63 to set on aligned shoulders 72 of block 63 and 73 of housing 45.

Through it is not shown because it is not necessary for understanding the invention, it is preferred that, after line connection is made with line connectors 64, the connections be potted in a permanent resin (not shown), such as epoxy, by filling well 75, formed by collar 76, with. epoxy resin or some other suitable liquid, hardenable potting material. Mouth end of housing 45 is provided with outside threads 81. Receptacle face electrical connectors are molded in place in front block '51. However, ground connector 86 merely passes through block 51. Thus passageways 89 do not represent openings that actually exist in front block SI, but rather indicate the extent of the insulating resin around face connectors 85, fixed therein, which are molded in place. However passageway 88 is an actual opening only slightly larger than ground connector 86, which is molded in place, i.e. fixed to,

rear block 63. Connector 86 passes through the entire receptacle, first passing through elongated opening 87 in switch rotor 52, then through snugly fitting opening 88 in front block 51.

Face connectors 85 and ground connector 86 pass through insulating faceplate, generally 90. Springs 94 which are positioned around connectors 85 keep insulating faceplate 90 away from front block 51. Insulating faceplate 90 is retained in position by abutment against an opposing portion of polarizing ring 98 held by retaining collar 99. Collar 99 is threaded on the inside to engage threads 81 on housing 45. Polarizing ring 98 is thus placed over the mouth end 80 of housing 45 and is retained thereon by retaining ring 99. Threads 112 on retaining ring 99 mate with corresponding threads on cap 42. Retaining ring 99 is jammed or otherwise secured to housing 45 during the course of manufacture to make it impossible, or at least extremely difficult, to tamper with, or expose energized internal components once the unit is installed.

MECHANICAL PROGRAMMER In the illustrated embodiment a pair of identical one-piece sleeve segments, generally 46, 46', serve as master programming elements to provide foolproof control and assurance of proper relationship in the functional status of the various operating components. Of specific interest, in connection with the rolling-butt switch of this invention, is the fact that the programmer ultimately controls the relative position of the switch means.

Mechanical control, or programmer, generally 46, 46, is fitted with three major control elements namely plug lock finger 115 which extends through slot 116 to the interior of housing 45: a lockout device (not shown since it does not constitute part of the present invention) which extends through slot 119, 119 of housing 45; and line switch control cam 121, 121 which passes through slot 122 into the interior of housing 45. As perhaps best seen in FIG. 2, mechanical programming means 46 comprises a collar segment having outwardly beveled edges 124. Programmer 46 keys into a mating recess in actuator ring 50. Programmer 46' is identical to programmer 46. Thus, in assembly mechanical programmer 46, 46 are placed around housing 45 with control elements 115, and 121 extending into or through corresponding slots 116, 122 in housing 45. Thus, bottom edge 127 of programmers 46, 46' rest on shoulder 128 of housing 45 and the programmers are pressed against the external circumference of housing 45. Actuator ring 50 is fitted over mouth end 80 of housing 45 and down over housing 45 and over programmers 46, 46, thus fixing elements 46, 46 with respect to rotation of actuator ring 50. When actuator ring 50 has been lowered over both housing 45 and programmers 46, 46' until bottom edge 130 of actuator ring 50 rests on shoulder 131 of housing 45, groove 133 positioned near shoulder 131 and ring 50 retain sealing means 134. Actuator ring 50 both maintains mechanical programmer elements 46, 46' in position against external surface of housing 45 and moreover fixes the position mechanical programming elements 46, 46' with respect to each other, i.e., diametrically opposite each other and provides means for manually selecting positions of program elements 46,46.

Generally speaking the details of the mechanism for locking actuator ring 50 against rotation, and for locking the plug into the receptacle will not be included herein since these features are described in a copending application Ser. No., 865,551, filed Oct. 13, 1969, and since these features are not essential to the understanding of the subject matter of this particular application. However, the automatic programmer lock mechanism includes pin I37, bolt 138, spring bias means, generally 139, and lock support 143.

OPERATING MECHANISM FOR SWITCH Major components of the line switch mechanism, generally 61, are perhaps best understood through a consideration of FIGS. 1 through 5. Switch mechanism 61 includes a pair of telescoping arms 147 which are biased outwardly by springbiasing means 148. Rollers 150, 150' are rotatably supported near the end of telescoping arms 147. This structure is thus self-balancing. Radial forces exerted on wheels 150, 150' are necessarily equal, since they are on opposite ends of the same spring means 148.

Flat-headed shoulder bolts 152 retain telescoping arms 147 on hub 154 of shaft 155. Bolts 152 pass loosely through slot 156 into telescoping arms 147. Bolts 152 thus permit movement of telescoping arms 147 in a radial direction, even though they fix arms 147 in hub 157 with respect to rotational movement. Rotation of arms 147 thus causes rotation of hub 154 in shaft 155. Rotor 52 is secured to rotatable shaft by means of pin 157 and retaining spring (e.g., a C washer) 158. Pin 157 resides in slot 159, perhaps best seen in FIG. 10, and is retained therein by C washer 158 to fix rotor 52 to shaft 155. Hence rotation of shaft 155, rotor 52 and telescoping arms 147 occurs together.

SWITCH STRUCTURE Rotor 52 is provided with a plurality of upper and lower elongated depressions 161 and 162, respectively, in which front connector contacts 163 and line connector contacts 164, respectively, reside. Contacts 163 and 164 are fixed with respect to receptacle 45. Contact bridges, generally 166, comprise a central support electrically conducting section 168, curved contact faces 169, preferably made of silver, central spring-retaining post 171, and biasing spring 172. Contact bridges 166 are passed through openings 174 at an angle and are aligned so that central support structure 168 abuts edge of rotor 152. Rotor 152 defines two abutments at opposite sides of opening 174; spring 172 being seated against one of these abutments and the bridge 166 being seated against the other abutment 175. Bridges, 166, are urged against edge 175 due to the biasing effect of spring 172. Contact faces 169 are sufficiently wider than the corresponding dimension of opening 174 to prevent dropping of contact element through opening 174. Thus shoulders 177 slide along and rest upon, the upper edges 179 of opening 174 of rotor 152.

The line switch mechanism, generally 61, has two static positions, namely the power-off position illustrated in FIGS. 2, 3, 12, and 15 and the power-on position illustrated in FIGS. 4, 5 and 14. The entire rotor and contact system is maintained in the power-off position whenever rollers 150, 150' are on the power-off side of center 181, 181' of control cam 121, 121', respectively. When wheels 150, 150' are not bearing against inclined surfaces 183, 184, the outwardly biasing action of spring-biasing means 148 forces braker 186 located at the extreme ends of switch control means 61 against the interior wall of housing 45, thus preventing rotational motion in either direction.

OPERATION OF SWITCH Specifically referring to FIG. 2, clockwise rotation of actuating ring 50 causes clockwise rotation of mechanical programmer 46, 46', brining inclined cam surfaces 183, 183 to bear against wheels 150, 150 respectively. This action urges wheels 150, 150 in two ways: (a) in a clockwise direction thus urging rotor 52 against abutting stop 68 as seen in FIG. 29, and (b) radially toward the center of the mechanism. The inward radial movement lifts brake 186 from its contact with housing 45. As soon as clockwise rotation continues until wheels 150, 150 pass over the center," the outwardly biasing action of spring-bias means 148 drives the switch control mechanism in a counterclockwise direction as wheels 150, 150 roll down inclined surface 148. Switch control mechanism 61 comes to rest when the positions illustrated in FIGS. 4, 5, and 14 are obtained, i.e., rotor 52 comes to rest against stop 68 at the other edge of slot 69, and detents of programmers 46, 46' come to rest at the edge of their respective slots also. Thus outwardly being action of bias means 148 drives rotor 52 against stop 68, and drives both ends of each of the contact bridges, generally 166, against line and connector contacts 164 and 163, respectively, both of which are fiat faced.

As illustrated in FIGS. 11 through 15, contact bridge, generally 166, abuts leading edge forming an abutment 175 of rotor 52 when the mechanism is in the power-off position. It is further noted that leading edge 175 forms an angle (see FIG. 11) with the rotor radius. Thus the entire bridge is carried on the bias, or at an angle 0, with respect to the rotor radius, as perhaps best seen in FIG. 12, when the rotor is in the poweroffposition. As the rotor rotates to the power-on position, initial contact between cured contact surface 169 and. flat-base contact surface 163, or 164, occurs atpoint P as illustrated in FIG. 13. Continued rotation of rotor 52 to power-on position illustrated in FIG. 14, causes compression of spring-bias means 172 and brings the central support structure 168 away from leading edge 175 of rotor 52. In the poweroff position, contact bridge 166 floats against compression spring means 172. In the fraction of a second after initial contact at P each bridge 166 rotates separately until curve faces 169, 169' come to rest on flat bases 163, or 164 at P, as shown in FIG. 14.

Movement of rotor 52 in the reverse direction, i.e., in the counterclockwise direction to the power-off position, first brings edge 175 against center support portion 168 causing each bridge structure 166 to pivot slightly until bridge 166 completely abuts leading edge 175, at which time contacts between curve faces 169, 169' and flat bases 163, or 164 is then finally broken. Thus, it is seen that the initial and final contact between bridge contact and stationary contact occurs at one point, namely I., while the at-rest contact is a different point, namely, P, which is spaced apart from contact point P This particular configuration is extremely advantageous since arcing, and damage due to arcing, at the making and breaking of contact occurs at point P and the smoothseparate rotation of the contact faces to operating abutment at point P, provides undamaged surfaces for the operational contacts.

Thus rotation of collar 50 in a clockwise direction from position 2 to position 3 illustrated inlFlG. 2 causes inclined surfaces 183, 183 to raise wheels 150, 150' over the center 18], 181', thereby causing switch mechanisms, generally 61, to snap abruptly to the power-on position described in detail above. Rotation of activation collar 50 and programming elements 46, 46' from position 3 to position 2 illustrated in FIG. 2 causes the switch mechanism, generally 61, to snap to the power-off condition as hereinbefore described.

ACHIEVEMENT The unique rolling-butt switchmechanism of this invention provides controlled arc positioning in which the touching and braking occurs at a contact point which is different and spaced apart from the working conducting surface. Thus, the risk of vaporization of metal which often occurs during arcing at high voltage or current and which causes some pitting, and piling and an irregular surface at the touch and break point does not interfere with the high-quality operating contact which occurs at a point spaced apart from the touch and break point. Test models have been run two times through a l0,000 operation cycle to test longevity of the purely mechanical factors, and once through 10,000 operations cycle under electrical operating conditions at normal ratings (60 and 100 amperes). No lessening of efficiency was observed as a consequence of the test cycle and no substantial damage was observed at the contact point of contact surfaces of contacts 169, 163.

Another advantage of the combination of the rolling-butt switch of this invention with the outwardly biased over-thecenter mechanism is the complete balancing of forces, and moreover the snap-open and snap-close feature provides high speed at the opening and closing which tends to break open the switch if stuck, and which eliminates current ripple or hovering of contacts in close proximity to prevent relatively sustained arcing. Moreover the rolling of the contact surfaces,

one over the other, is achieved in essence without providing moving parts in the usual sense since the rolling is achieved by a wobble of bridge 166 against a biasing means such as spring 172 when bridge 169 is released from biased engagement with its support-rotor 52, and vice versa. Thus, the rolling-butt switch of this invention need not be used with the particular over-the-center mechanism described herein, although a fast touch and break action provided by a conventional over-the-center mechanism is preferred to a relatively slow touch and break motion. It is believed that one of the reasons for the long life of the switch of this invention is the fact that, as described above, the contact elements approach each other along a line which is substantially normal or perpendicular to the flat faced contact 163, i.e., along the circumference of a circle, having its center at the center of rotor 52, drawn through point P The, approach of the contact elements, i.e. 169, 169' to 163, 164 is. direct, (along a line approximately perpendicular to flat-faced contacts 163, 164) ratherthan oblique, (or along a, line forming an acute angle with flat-faced elements 163, 164) and thus the time lapse expended in the approach (and separation) of'the elements is minimal, and chance of arcing during approach (or separation) is also minimal. Moreover, in a preferred embodiment, a connecting bridge 166 resides on insulating rotor 52. In such embodiments the effective distance between the line contact and front contact is twice the distance between actual contacts, and this, too, is believed to be another of many factors which contribute to the long life of the preferredswitch of this invention. As actual contacts approach each other, their effective distance apart is twice the actual distance apart between individual contacts and their effective velocity is twice their actual velocity.

I claim:

1. In an electrical switch having a pair of contacts at least a first of which is moveable a given distance along a line toward and away from the second between rest positions to make and break an electrical circuit with at least one of said contacts having a curved face and means supportinga given contact so that when the contacts are moving between the positions where they first make and just when the contacts finally break the given contact has one angular orientation with respect to the other contact so that the location of contact on the curved face is at one point thereon and when the contacts are at rest at the make position the given contact has another angular orientation so that the location of contact is at another point on the curved face, the improvement wherein said means comprises:

a support member for said given contact, said support defining spaced abutments transverse to said line, said given contact having at least a portion between said abutments, and 1 a spring in compression between one of said abutments and said portion, said spring resiliently urging said given contact toward said other abutment and aligned so that its resultant force, when said given contact is unrestrained by the other abutment, extends through said other point whereby said given contact will assume said other angular orientation generally normal to said resultant force when at rest against said other contact,

said other abutment at an angle with respect to said other contact and being positioned sufficiently close to the one abutment to contact said portion when the two contacts are separated and thus to restrain said given contact from further movement toward the other contact and positioned other than normal to said resultant force to align said given contact in an orientation other than normal to said resultant force so that the given contact has said one angular orientation,

said contacts being positioned adistance apart such that when the movement of said given distance occurs said given contact is pushed away from said other abutment by engagement with the other contact.

2. in a butt-contact bridge switch having a pair of fixed, spaced-apart, open circuit contact elements and a pair of electrically connected, moveable bridge contact element, and means for bringing the moveable contact elements together with the fixed contact element in an on position, and separating them to an off position, said moveable bridge elements being adapted to form a conductive bridge between said open circuit elements when the switch is at rest in an on position, the improvement in which:

each element of one of the pair of contact elements has a convex contact surface;

the switch includes pivotal support means for pivoting each of the pair of movable contact elements with respect to its respective opposing fixed contact element after the contact elements have been brought together in the on" position, whereby initial contact between them occurs at a first point of contact between the opposing elements, and whereby the operating point of contact between the opposing elements is a second point, the second point being spaced apart from the first point;

the switch also includes means for pivoting each of the moveable contact elements with respect to its respective opposing fixed contact elements immediately before the contacting elements are separating from each other whereby the contact elements separate from a contacting point which is spaced apart from the contacting point utilized while the switch is at rest on its on" position;

said means for bringing the contact elements together being a rotor carrying said bridge contact elements; and

said switch including:

means connected to the rotor for pivoting said rotor to the first, on" position and to the second, off position;

flexible, resilient support means for attaching said conductive bridge to said rotor; and

pivoting means on said rotor for pivoting said bridge around a longitudinal axis of the bridge, said pivoting means including stop means fixed to said rotor, against which stop means said flexible resilient support means urges the said bridge when the contact elements are in said off" position, said stop means being oriented to pivot the bridge butting thereagainst away from the position normally supported by the flexible support means, said stop means fixing the bridge butting there against with respect to said rotor when the rotor is in the off position, whereby, upon rotation of the rotor in the direction of the off position, the resilient support means urges the bridge against said stop means thereby pivoting said bridge and fixing said bridge with respect to the rotor, and upon continued movement in the off direction said moveable contact elements away from the open circuit contact elements, and whereby rotation of the rotor toward the on position brings the moveable contact elements together with the fixed line contact elements, and whereby continued rotation of the,rotor separates the rotor stop means from the bridge whereby the flexible resilient support means pivot the movable contact elements to a point of operating contact which is spaced apart from the point at which the contact elements first abut.

3. In a switch as set forth in claim ll wherein said support member is fiat with two sides, including an insulator member having portions adjacent said sides respectively, a first said other contact being secured to one portion of said insulator member, a second other contact being secured to the other portion of said insulator member and aligned with the first other contact, a first said given contact being positioned adjacent the first other contact, a second given contact being positioned adjacent the second other contact, a contact bridge connecting the two given contacts and forming said portion thereof,

one of said members being moveable along said line with respect to the other member.

* i IR IQ IINITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pa t N 3,617,672 Dated November 2, 1971 Invent0r(s) Namik O. Atakkaan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, Line 33, "on" after "pivoting" should be deleted. Column 2, Line 40, after "switch-rotor" should be inserted Column 2, Line 59, "set" should be -seat.

Column 2, Line 61, "Through" should be Though-. Column 4, Line 60, "brining" should be bringing-. Column 4, Line 75, "being" should be --biasing-. Column 5 Line 13, "cured" should be --curved.

Column 8, Line 14, after "elements" should be inserted -move.

Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM POJOSO {10-69) uscoMM-Dc 50376-P69 U S GOVERNHENY PRVNYING OFFICE 1969 0-365-334 

1. In an electrical switch having a pair of contacts at least a first of which is moveable a given distance along a line toward and away from the second Between rest positions to make and break an electrical circuit with at least one of said contacts having a curved face and means supporting a given contact so that when the contacts are moving between the positions where they first make and just when the contacts finally break the given contact has one angular orientation with respect to the other contact so that the location of contact on the curved face is at one point thereon and when the contacts are at rest at the make position the given contact has another angular orientation so that the location of contact is at another point on the curved face, the improvement wherein said means comprises: a support member for said given contact, said support defining spaced abutments transverse to said line, said given contact having at least a portion between said abutments, and a spring in compression between one of said abutments and said portion, said spring resiliently urging said given contact toward said other abutment and aligned so that its resultant force, when said given contact is unrestrained by the other abutment, extends through said other point whereby said given contact will assume said other angular orientation generally normal to said resultant force when at rest against said other contact, said other abutment at an angle with respect to said other contact and being positioned sufficiently close to the one abutment to contact said portion when the two contacts are separated and thus to restrain said given contact from further movement toward the other contact and positioned other than normal to said resultant force to align said given contact in an orientation other than normal to said resultant force so that the given contact has said one angular orientation, said contacts being positioned a distance apart such that when the movement of said given distance occurs said given contact is pushed away from said other abutment by engagement with the other contact.
 2. In a butt-contact bridge switch having a pair of fixed, spaced-apart, open circuit contact elements and a pair of electrically connected, moveable bridge contact element, and means for bringing the moveable contact elements together with the fixed contact element in an ''''on'''' position, and separating them to an ''''off'''' position, said moveable bridge elements being adapted to form a conductive bridge between said open circuit elements when the switch is at rest in an ''''on'''' position, the improvement in which: each element of one of the pair of contact elements has a convex contact surface; the switch includes pivotal support means for pivoting each of the pair of movable contact elements with respect to its respective opposing fixed contact element after the contact elements have been brought together in the ''''on'''' position, whereby initial contact between them occurs at a first point of contact between the opposing elements, and whereby the operating point of contact between the opposing elements is a second point, the second point being spaced apart from the first point; the switch also includes means for pivoting each of the moveable contact elements with respect to its respective opposing fixed contact elements immediately before the contacting elements are separating from each other whereby the contact elements separate from a contacting point which is spaced apart from the contacting point utilized while the switch is at rest on its ''''on'''' position; said means for bringing the contact elements together being a rotor carrying said bridge contact elements; and said switch including: means connected to the rotor for pivoting said rotor to the first, ''''on'''' position and to the second, ''''off'''' position; flexible, resilient support means for attaching said conductive bridge to said rotor; and pivoting means on said rotor for pivoting said bridge around a longitudinal axis of the bridge, said pivoting means including stop means fixed to said rotor, against whIch stop means said flexible resilient support means urges the said bridge when the contact elements are in said ''''off'''' position, said stop means being oriented to pivot the bridge butting thereagainst away from the position normally supported by the flexible support means, said stop means fixing the bridge butting there against with respect to said rotor when the rotor is in the ''''off'''' position, whereby, upon rotation of the rotor in the direction of the ''''off'''' position, the resilient support means urges the bridge against said stop means thereby pivoting said bridge and fixing said bridge with respect to the rotor, and upon continued movement in the ''''off'''' direction said moveable contact elements away from the open circuit contact elements, and whereby rotation of the rotor toward the ''''on'''' position brings the moveable contact elements together with the fixed line contact elements, and whereby continued rotation of the rotor separates the rotor stop means from the bridge whereby the flexible resilient support means pivot the movable contact elements to a point of operating contact which is spaced apart from the point at which the contact elements first abut.
 3. In a switch as set forth in claim 1 wherein said support member is flat with two sides, including an insulator member having portions adjacent said sides respectively, a first said other contact being secured to one portion of said insulator member, a second other contact being secured to the other portion of said insulator member and aligned with the first other contact, a first said given contact being positioned adjacent the first other contact, a second given contact being positioned adjacent the second other contact, a contact bridge connecting the two given contacts and forming said portion thereof, one of said members being moveable along said line with respect to the other member. 